.\" Copyright (c) 2011 Kai Wang
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.Dd June 4, 2011
.Os
.Dt DWARF_GET_FDE_INFO_FOR_REG 3
.Sh NAME
.Nm dwarf_get_fde_info_for_reg
.Nd retrieve register rule
.Sh LIBRARY
.Lb libdwarf
.Sh SYNOPSIS
.In libdwarf.h
.Ft int
.Fo dwarf_get_fde_info_for_reg
.Fa "Dwarf_Fde fde"
.Fa "Dwarf_Half table_column"
.Fa "Dwarf_Addr pc"
.Fa "Dwarf_Signed *offset_relevant"
.Fa "Dwarf_Signed *register_num"
.Fa "Dwarf_Signed *offset"
.Fa "Dwarf_Addr *row_pc"
.Fa "Dwarf_Error *error"
.Fc
.Sh DESCRIPTION
Function
.Fn dwarf_get_fde_info_for_reg
retrieves a register rule from the register rule table associated with
a given FDE descriptor, given a program counter address and rule
column number.
.Pp
Argument
.Ar fde
should reference a valid DWARF FDE descriptor.
.Pp
Arugment
.Ar table_column
should hold the column number of the register rule desired.
.Pp
Argument
.Ar pc
should hold the program counter address to be used to locate the
desired register rule row.
.Pp
On successful execution,
.Fn dwarf_get_fde_info_for_reg
stores information about the register rule found into the locations
pointed to by the arguments
.Ar offset_relevant ,
.Ar register_num ,
.Ar offset
and
.Ar row_pc .
.Pp
If there is an offset value associated with the register rule,
the location pointed to by argument
.Ar offset_relevant
will be set to 1.
.Pp
Argument
.Ar register_num
should point to a location which will hold the register number associated
with the register rule.
.Pp
Argument
.Ar offset
should point to a location which will be set to the offset value
associated with the register rule, or to 0 if the register rule
does not have an offset value.
.Pp
Argument
.Ar row_pc
should point to a location which will be set to the lowest program
counter address associated with the register rule found.
.Pp
If argument
.Ar err
is not NULL, it will be used to return an error descriptor in case
of an error. 
.Ss COMPATIBILITY
Function
.Fn dwarf_get_fde_info_for_reg
is deprecated since it only supports DWARF2 frame sections.
Applications should instead use function
.Xr dwarf_get_fde_info_for_reg3 3
which supports both DWARF2 and DWARF3 frame sections.
.Sh RETURN VALUES
Function
.Fn dwarf_get_fde_info_for_reg
returns
.Dv DW_DLV_OK
when it succeeds.
In case of an error, it returns
.Dv DW_DLV_ERROR
and sets the argument
.Ar err .
.Sh ERRORS
Function
.Fn dwarf_get_fde_info_for_reg
can fail with:
.Bl -tag -width ".Bq Er DW_DLE_FRAME_TABLE_COL_BAD"
.It Bq Er DW_DLE_ARGUMENT
One of the arguments
.Ar fde ,
.Ar offset_relevant ,
.Ar register_num ,
.Ar offset
or
.Ar row_pc
was NULL.
.It Bq Er DW_DLE_FRAME_TABLE_COL_BAD
The column number provided in argument
.Ar table_column
was too large.
.It Bq Er DW_DLE_PC_NOT_IN_FDE_RANGE
The program counter value provided in argument
.Ar pc
did not fall in the range covered by argument
.Ar fde .
.El
.Sh SEE ALSO
.Xr dwarf 3 ,
.Xr dwarf_get_fde_at_pc 3 ,
.Xr dwarf_get_fde_info_for_all_regs 3 ,
.Xr dwarf_get_fde_info_for_all_regs3 3 ,
.Xr dwarf_get_fde_info_for_cfa_reg3 3 ,
.Xr dwarf_get_fde_info_for_reg3 3 ,
.Xr dwarf_get_fde_n 3 ,
.Xr dwarf_set_frame_cfa_value 3 ,
.Xr dwarf_set_frame_rule_table_size 3 ,
.Xr dwarf_set_frame_rule_initial_value 3 ,
.Xr dwarf_set_frame_same_value 3 ,
.Xr dwarf_set_frame_undefined_value 3
